Oh, yes, the D-Box countersteers INITIALLY, then releases control back to the driver. This all happens within a second. What it does is reacts to the slide. When you dial out the gain, it lessens the amount of "steer" the D-Box gives, but retains some of the speed of reaction time. Your daughter will still need to control the drift, once it is initiated, the D-Box just helps get the car sideways without spinning out. This allows your daughter to learn what she needs to do, in order to control a drift.
Turning down the gain, while SLOWLY decreasing the radius of turns over time is a good way for her to pick up her skills. She will learn how to keep the car from spinning out, theless gain there is. Once the D-box is turned down so low that the wheels barely turn, or not at all, is the time it should be removed. Your daughter should be drifting on her own, very well by then!